Non- or mal-union of the clavicle is reported to occur in up to 15 % of conservatively treated fractures: the purpose of this systematic review is to examine the evidence for the use of external fixation in the treatment of clavicular non-union. We performed a search of MEDLINE and Embase, including all papers using external fixators for the treatment of clavicular non-union. Four papers satisfied our eligibility criteria: three case series and one case-control study. Level of evidence and quality assessment scoring were performed using published methods. Due to the heterogeneity of the study populations and interventions, no attempt at meta-analysis was made. External fixation in hypertrophic non-union of the clavicle, but not atrophic non-union, appears to be a reasonable treatment option. A pragmatic, multicentre, randomised controlled trial comparing external fixation and open reduction internal fixation in the treatment of hypertrophic non-union of the clavicle would be valuable.